The surfaces of drywall materials defining wall and ceiling surfaces are commonly coated with texture materials. Texture materials are coatings that are deposited in discrete drops that dry to form a bumpy, irregular texture on the destination surface. Texture materials are commonly applied using a hopper gun connected to a source of pressurized air. However, when only a small area is to be coated or an existing textured surface is repaired, texture materials are typically applied using an aerosol dispensing system.
An aerosol dispensing system for dispensing texture material typically comprises a container assembly, a valve assembly, and an outlet assembly. The container assembly contains the texture material and a propellant material. The propellant material pressurizes the texture material within the container assembly. The valve assembly is mounted to the container assembly in a normally closed configuration but can be placed in an open configuration to define a dispensing path along which the pressurized texture material is forced out of the container assembly by the propellant material. Displacement of the outlet assembly places the valve assembly in the open configuration. The outlet assembly defines a portion of the outlet path and is configured such that the texture material is applied to the destination surface in an applied texture pattern.
The texture material dispensed by an aerosol dispensing system may employ a solvent base, a water base, or a base containing a combination of water and water soluble solvents. A solvent based texture material dries quickly but can be malodorous and may require the use of complementary solvent cleaners for clean up. A water based texture material is typically not malodorous and can be cleaned using water but can take significantly longer to dry. A water/solvent based texture material can be cleaned using water, is typically not unacceptably malodorous, and has a dry time somewhere between solvent based and water based texture materials.
The propellant used by aerosol dispensing systems for texture materials may simply be a compressed inert gas such as air or nitrogen. More typically, the propellant used by aerosol dispensing systems is a bi-phase propellant material, including mixtures of volatile hydrocarbons such as propane, n-butane, isobutane, dimethyl ether (DME), and methylethyl ether.
At room temperature, bi-phase propellant materials typically exist in both liquid and vapor states within the container assembly. Prior to use, the vapor portion of the bi-phase propellant material is pressurized to an equilibrium pressure. When the valve assembly is placed in its open configuration, the vapor portion of the bi-phase propellant material forces the texture material out of the container assembly along the dispensing path.
When the valve assembly returns to its closed position, part of the liquid portion of the bi-phase propellant material changes to the vapor state because of the drop in pressure within the container assembly. The vapor portion of the propellant material returns the pressure within the container assembly to the equilibrium value in preparation for the next time texture material is to be dispensed from the aerosol dispensing system.
The container assembly typically comprises a metal tube structure formed by a rectangular metal sheet that is rolled and joined at two overlapping edges to form a seam. A bottom cap and end cap are welded or crimped onto the tube structure. The valve assembly and the outlet assembly are typically supported by the end cap.
Aerosol container assemblies are typically made of either tin-plated steel or aluminum. Aluminum container assemblies are typically used for water based or water/solvent based texture materials because the water in the formulation promotes corrosion and aluminum is less susceptible to corrosion. However, the costs and availability of aluminum and tin-plated steel aerosol container assemblies may differ.
The need thus exists for formulations of either water based or water/solvent based texture materials that may be used in either aluminum or tin-plated steel aerosol container assemblies without significant risk of corrosion.